Cross-sectional study of serum reactivity to Anisakis simplex in healthy adults in Niterói, Brazil

Although the incidence of anisakiasis is rising worldwide, its frequency is still unknown in Brazil. The aim of this study was to verify immunoreactivity to Anisakis simplex antigens in healthy adults and determine its possible relationship with frequency of fish consumption and allergy symptoms. A prospective cross-sectional study was carried out with 67 volunteers recruited from a military facility in Niterói, Brazil. The subjects completed a structured questionnaire and serum titers of specific anti-Anisakis IgE and IgG antibodies were measured. The association between frequency of fish intake and IgE reactivity was evaluated by Fisher's exact test. Almost all subjects (97.0%, 65/67) that consumed seafood; 64.6% (42/65) ate fish at least once weekly. Of all seafood consumers, 56.9% (37/65) reported allergy symptoms, being gut allergies most often cited (35.5%). IgE seroreactivity to Anisakis simplex was found in 20.9% of subjects (14/67), with 13.4% (9/67) reacting exclusively to somatic antigen, 3.0% (2/67) exclusively to excretory/secretory antigens and 4.5% (3/67) to both antigens. There was a significant association between frequency of fish consumption and positive serology (p = 0.019). An immunoblot assay for Anisakis antigens showed different positive bands for IgG. The direct relationship between ELISA reactivity and frequency of fish intake and absence of association with allergy symptoms suggests previous contact with Anisakis simplex antigens.